Method of producing a direct positive photographic relief image employing a photoconductive-binder element

ABSTRACT

Methods are disclosed for making a direct positive photographic relief image and dye transfer prints therefrom by imagewise exposing an imaging medium comprising a photoconductor dispersed in a binder therefor, developing the medium with a developer depositing free metal in radiation-exposed areas, reoxidizing the free metal to metal ions in the presence of metal ion-activated softening agent for said binder, removing softened portions of the to produce said positive relief image, and, for preparing prints, taking up dye in remaining portions of the binder and transferring dye therefrom to a receptor sheet.

United States Patent [72] Inventor Robert Hicks Sprague Chelmstord, Mass.

[21] Appl. No. 713,022

[22] Filed Mar. 14, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Itek Corporation Lexington, Mass.

[54] METHOD OF PRODUCING A DIRECT POSITIVE PHOTOGRAPHIC RELIEF IMAGE EMPLOYING A PHOTOCONDUCTIVE-BINDER ELEMENT 8 Claims, 2 Drawing Figs.

[52] U.S.'Cl 96/1.2,

96/1 R, 101/463 R, 101/468 R, 101/471 R, 117/17.5 R

[51] Int. Cl 603g 13/00 [50] Field of Search 96/].2, 1.5,

[56] References Cited UNITED STATES PATENTS 2,257,105 9/1941 Champion et a1 101/149 3,337,340 8/1967 Matkan 96/1 3,380,823 4/1968 Gold 96/27 3,429,706 2/1969 Shepard 96/64 3,481,736 12/1969 Ruff 96/28 Primary Examiner-George F. Lesmes Assistant Examiner-M. B. Wittenberg Attorneys-Homer 0, Blair, Robert L. Nathans and W. Gary Goodson ABSTRACT: Methods are disclosed for making a direct positive photographic relief image and dye transfer prints therefrom by imagewise exposing an imaging medium comprising a photoconductor dispersed in a binder therefor, developing the medium with a developer depositing free metal in radiation-exposed areas, reoxidizing the free metal to metal ions in the presence of metal ion-activated softening agent for said binder, removing softened portions of the to produce said positive relief image, and, for preparing prints, taking up dye in remaining portions of the binder and transferring dye therefrom to a receptor sheet.

PAIENTEDucI 2s IBYI SHEET 10F 2 ORIGINAL IMAGE: R D GREEN BLUE COLOR SEPARATION IMAGES:

(REDHSEPAVRATION NEGATIVE) X D PA AT ,QN PQ$IT X X GREEN SER RA N TWE X X EIL E SEPARATIONWPOSITIVE X X EXPOSURE and DEVELOPMENT:

IMAQING.MEQIEMWEIB RED X IMAGING MEDIUM FOR GREEN X IMAGING MEDIUM FOR BLUE X SELECTIVE BINDER REMOVAL:

E LLEFmWL....., B B

ER EENHBELIEEW .7 E B B B E URELIEFUM B B DYE TRANSFER:

R E D R E LI E5 CYAN CYA N EE RELIEF m MAGENTA MAGENTA LLI E-BLL E. L. YELLOW YELLOW DYE TRANSFER IMAGE: RED GREEN BLUE X" IND/CA T55 RADIATION EXPOSED AND DEVELOPED PORT/0N5.

"B m/0M1: T55 THE PRESENCE OF UNREMO VED BINDER.

FIG.

R0 BERT H; SPRA 61/5 I N VENTOR.

ATTORNEY.

PATENTEUDET 26 Ian SHEET 20F 2 ORIGINAL IMAGE: RED GREEN BLUE EXPOSURE and DEVELOPMENT:

EEQENSJTW E. M U M X QREEN SENSITIVE MEDIUM X gLuE SENSITIVE MEDIUM X E LECTIVE BINDER REMOVAL:

RED ELIEF w B B GREEN RELIEF B B EILUE RELIEF w B B DYE TRANSFER;

BEPMREL FM CYAN CYAN GREEN BEIIEEWMW MAGENTA MAGENTA 5&9? R LIE ,...Y. YELLOW DYE TRANSFER IMAGE: RED GREEN BLUE X" IND/CA r55 RA 0/4 r/0/v- EXPOSED AND ammo/ 50 PORT/0N.

"B"//VD/CA r55 THE PRESENCE OF UNREMOVEO BINDER.

ROBERT H. .S'PRAGUE INVENTOR.

BY 4 25 W A TTORNEK METHOD OF PRODUCING A DIRECT POSITIVE PI'IOTOGRAPIIIC RELIEF IMAGE EMPLOYING A PI-IOTOCONDUC'IIVE-IIINDER ELEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to methods for making direct positive photographic relief images and to methods for making dye transfer prints, including full color dye transfer prints, therefrom; to such direct positive photographic relief images adaptable to making dye transfer prints; and to photographic imaging media for preparing direct positive photographic relief images.

2. Description of the Prior Art Commonly owned US. Patent No. 3,380,828 issued Apr. 30, 1968 discloses photographic imaging media comprising a finely divided photoconductor. Exposure of such an imaging medium to actinic radiation such as visible or ultraviolet light activates the photoconductor, rendering it capable of effecting chemical reaction which can be utilized to develop a visible image in the medium. The finely divided photoconductor is usually present dispersed per se throughout a support layer such as of paper or plastic, or, dispersed in a binder therefor, forms a photosensitive layer on a support such as paper, metal foil, plastic, glass, or the like.

As known in the art, the photoconductorsof greatest utility for use in such imaging media are compounds formed between metals and elements of Group VIA of the Periodic Table, e.g., oxides, sulfides, selenides, and tellurides. Preferred materials from the point of view of color, light sensitivity, ease of development and the like are titanium dioxide and zinc oxide.

The latent image of activated photoconductor formed in such imaging media by imagewise exposure thereof can be suitably developed by applying image-forming materials to the media. Suitably image-forming materials include redox systems, for example systems containing reducible metal ions such as silver ions or other ions of metals at least as easily reducibleas ionic copper.

SUMMARY OF THE INVENTION According to the present invention, photographic imaging media comprising a photoconductor of the type disclosed in said copending application are employed for the preparation of direct positive photographic relief images adaptable to the preparation of dye transfer prints, including full color dye transfer prints. Thus, the present invention has particular utility for the preparation of dye transfer prints, including full color dye transfer prints, from photographic positives, including color positives.

According to the present invention, a photographic imaging medium comprising a finely divided photoconductor dispersed through a binder, said photoconductor and binder suitably being present as a photosensitive layer coated on a supporting substrate such as of paper, metal, glass, plastic, or the like, is exposed to imaging radiation which activates the photoconductor in radiation-exposed areas. Those portions of the photographic medium containing activated photoconductor are next developed by contacting the exposed medium with a developing agent comprising metal ions which are reduced by the activated photoconductor to form a deposit of free metal in the binder.

Next, the free metal deposited in radiation-exposed areas is reoxidized to form metal ions dispersed throughout the binder in radiation-stuck portions of the photographic medium. This reoxidation is effected in the presence of a metal ion-activated softening agent for said binder so that those portions of the binder surrounding the metal ions formed in the exposed medium by reoxidation become softened. At this stage, a negative copy of the original image is now reproduced in the exposed medium by a pattern of softened binder in those portions of the medium which have been struck by radiation.

The softened binder is next removed by mechanical or chemical means, leaving a positive photographic relief offthe original image reproduced on the support layer by raised (unremoved) portions of the binder in areas not exposed to imaging radiation.

The photographic relief so produced can be viewed as a positive copy of the original image. If desired, either the support layer forming the background of the relief, or the raised binder portions, or both, can be dyed or stained to improve image visibility. The relief can be used as a dye transfer medium by applying dye to the unremoved binder portions; The dye is then transferred to a receptor sheet. Also, by appropriate choice of the support layer and binder to emphasize differences in hydrophilicity and oleophilicity, a relief suitable for use as a lithographic plate can be prepared. By exposing a plurality of printing media to color separation positives, or to a color positive through color filters, said media in the latter case being differently dye-sensitized to be sensitive to red, green, or blue light, a set of relief images suitable for use in making full color dye transfer prints can be prepared according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT The methods and materials of the present invention are particularly useful in systems employing hardened gelatin as a binder for a photoconductor in an imaging medium.

In such a preferred embodiment, a photographic imaging medium comprising a support layer such as of paper having a finely divided photoconductor, such as finely divided titanium dioxide, dispersed throughout a hardened gelatin layer on said support, is exposed to imaging radiation as described. Lightstruck areas of the imaging medium are then developed by contact of the exposed medium with a developing agent com prising a dissolved metal salt, suitably a dissolved silver salt, resulting in the deposition of metal in the light-struck areas. The image so formed may by. intensified by techniques analogous to physical development. The metal image, e.g., a silver image, is next bleached in the presence of a softening agent for the gelatin. The medium is then washed to remove the gelatin, which has been solubilized in light-struck areas, leaving hardened gelatin in unexposed areas. I

Development with silver ion is conveniently done by contacting the exposed imaging medium with aqueous silver nitrate to form a metallic silver image in the medium. The image can be intensified by contact with a redox system, preferably an organic redox system such as hydroquinone, metol (p-methylamino phenol sulfate) or the like, which promotes further deposition of metal where metal is already present. The metal ion and redox system may be applied separately or in admixture.

Bleaching solutions having a softening effect on hardened gelatin layers are known in the photographic arts and are taught, for example, in Glafkides, Photographic Chemistry, "Vol. 2, Fountain Press, London (1960), page 668.

The direct positive photographic relief images prepared according to the present invention have numerous desirable properties. The reliefs of the present invention can be used to produce multiple copies by successive redyeings of the relief matrix with conventional light-fast transfer dyes. Also, the processing of the positive photographic relief images of the present invention is rapid. The initial development step involving precipitation of free metal is extremely rapid, generally requiring only a few seconds, and the bleaching and binder softening development step is also short. when the reliefs are used for making dye transfer prints, the rapidity of dye absorption and transfer is very rapid compared with reliefs prepared from conventional silver halide gelatin layers. Thus, even as little time as 5 seconds is usually sufficient for dye ,take'up by the binder according to the present invention, as compared with about 2 minutes for silver halide reliefs. Similarly, takenup dye is quickly released to a mordanted receptor sheet, e.g., 5 -l0 seconds, compared with as much as 2 minutes for conventional silver halide'relief layers. Conventional silver halide emulsion layers generally comprise a very hard tanned gelatin resistant even to removal by hot water up to 60 C. These layers only absorb and release dye slowly. Gelatin layers useful in making reliefs according to the present invention are untanned materials, hardened, for example with fonnaldehyde, only to be resistant to cold water but softening at 45 60 C. Dye take-up and transfer are much more rapid from such layers.

What is perhaps most important, the preparation of lightsensitive media suitable for making relief images and comprising a photoconductor of the type described is extremely simple. The media need neither be manufactured nor handled in the dark, as is absolutely necessary with silver halide, but, as known from said copending application and elsewhere in the art, photosensitive layers comprising a photoconductor can be applied to a substrate under ordinary conditions and only require densensitization by techniques such as heating or dark storage prior to exposure to imaging radiation. This should be contrasted with the extreme care required in the preparation, handling, and storage of silver halide emulsions.

The production of a relief image in a layered photographic imaging medium according to the invention depends on selective softening and/or removal of a photosensitive binder layer from a support layer. Thus, the medium is conventionally exposed to imaging radiation from its light-sensitive side to insure that softening and removal of the binder layer will occur in proportion to the amount of radiation received by the binder layer, i.e., that a complete removal of the binder layer from the support layer will only occur in those portions of the medium in which the light intensity is strongest, penetrating to the interface between the binder layer and support layer. As is also known in the art of preparing relief images by radiation induced softening of a binder layer, a light-attenuating agent is suitably dispersed in the binder layer of the imaging medium to control the depth of light penetration on exposure. For example, in panchromatic silver halide films used for the production of relief images, finely divided carbon is generally dispersed through the imaging medium as a moderator or attenuator. Alternatively, a yellow dye is often dispersed through silver halide layers for the same reason.

In the present invention, a moderator or attenuator is also suitably employed to control the depth of radiation penetration on exposure. In the preparation of positive relief images ancillary to producing full color dye transfer prints, the photoconductor in the imaging medium is, in one embodiment of the present invention, dye sensitized with known dye sensitizers to be receptive to red, green, or blue light. The dyes used for this sensitization are generally present in the binder layer in amounts sufiicient for the dye to act also as a moderator or attenuator, so that the need for carbon or an additional dye as a light moderator is obviated.

A first method for the preparation of a full color dye transfer print from a positive color image is explained below and outlined in FIG. 1 of the accompanying drawings.

As suggested in FIG. 1, a series of red, green, and blue separation positives is prepared from an original image comprising red, green, and blue portions. The preparation of such separation positives is well known in the art, and proceeds, for example, by the preparation of a set of red, green, and blue separation negatives by exposing conventional silver halide film to the original colored image using red, green, and blue filtered light respectively. As shown in FIG. 1 for the case of the red separation negative, those portions of the original image which are red would be exposed and developed in the red separation negative, while those portions of the original image which are green or blue would remain transparent.

Corresponding separation positives can be made by a simple contact process, again using conventional silver halide film. As shown in FIG. 1, the red separation positive is exposed and developed in those portions corresponding to green and blue areas of the original image. The finished red separation positive thus lacks density only in those portionsof the original image which are red.

Similar considerations would apply to the green and blue separation positives as suggested in FIG. 1.

For the preparation of a direct positive relief image according to the present invention, an image-forming medium according to the present invention is next exposed to activating radiation through the red separation positive. This activates the semiconductor in portions struck by the activating radiation, i.e., those portions corresponding to the red areas of the original image. These activated areas are then developed with a metal ion to precipitate free metal such as free silver in radiation-exposed areas.

In the next step, a red record relief is formed by selective binder removal employing a bleach reoxidizing the free metal to metal ion and a metal ion-activated softening agent for the binder. As is evident from FIG. 1, those portions of the red imaging medium in which free metal has been deposited are bleached with simultaneous removal of binder, leaving unremoved binder in those areas of the red relief which correspond with those portions of the original image which are green or blue.

Similarly, the green and blue imaging media are exposed and developed to deposit free metal, and then are bleached, selectively softened, and washed respectively to form a green record relief and a blue relief.

For the dye transfer step, a known suitable cyan dye conventional in the photographic arts for dye transfer processes is next taken up by unremoved portions of the binder in the red relief image and transferred from the raised portions thereof to a receptor sheet. Similarly, the green relief image is used to transfer conventional magenta dye to the same receptor sheet in register. Finally, the blue relief image is employed to transfer yellow dye in register to the image. As is evident from the drawing, this results in a positive reproduction of the original image, i.e., a direct positive print.

A second embodiment for the preparation of a full color dye transfer positive print from a positive color image dispensing with the need for color separation positives is explained below and is outlined in FIG. 2 of the accompanying drawings.

In this embodiment, a first imaging medium in which the photoconductor has been dye-sensitized to be sensitive to red light is first imagewise exposed to a positive color image, such as a positive color transparency, using a red filter. As shown in FIG. 2, those portions of the red sensitive medium corresponding with red areas in the original image are exposed and are subsequently developed by precipitation of free metal in the exposed areas.

The light-exposed and developed areas containing a free metal image are now treated with an oxidative bleach and softening agent. This results in selective softening of those portions of the binder in which the precipitated free metal is present, leaving unattacked raised areas of binder in those portions of the exposed medium corresponding with green and blue portions of the original image. This constitutes the red relief.

In a similar fashion, a green-sensitized photographic medium is exposed to the positive color image using a green filter and is developed with selective removal of binder to produce raised areas in those portions corresponding with other than green areas of the original image.

A third blue-sensitized medium is exposed through a blue filter with subsequent development and selective removal of binder to produce a blue relief.

A known suitably cyan dye conventional in the photographic arts for dye transfer processes is next taken up into the unremoved binder portions of the red relief image and is transferred from these portions to a receptor sheet. Similarly, the green relief is used to transfer a magenta dye in register, and the blue relief is employed to transfer a yellow dye in register to the receptor sheet. As is evident from FIG. 2, this results in a positive reproduction of FIG. 2 as compared with that outlined in FIG. 1 is evident. However, when color separation positives are already at hand, as for example in the prepara tion of photoengraved plates for full color printing, the making of prints therefrom is convenient. Indeed, the techniques of this invention are particularly useful in the printing arts for proofing screened color separation positives.

In the preparation of monochrome dye transfer prints using a direct positive relief image prepared according to the present invention, or in preparation offull color dye transfer prints London, either the technique involving color separation positives shown in FIG. 1 of the drawings or the shorter process-employing selectively dye-sensitized imaging mediaas outlined in FIG. 2, it may be desirable to'employ monochrome masking to decrease the contrast of the original image in order more closely to conform it with the density range of the imaging medium used to prepare the positive reliefs. As discussed in the section entitled Monochrome Masking in the Encyclopedia of Photography, Focal Press, London, p. 705 et seq., monochrome masking involves the production ofa weak, soft, positive contact print of the original image on another film. When developed, this weak negative of the original image is bound in register with the original positive. Exposures made through the combined original transparency and negative mask will be of considerably reduced contrast compared with exposures made through the unmasked transparency.

In the process outlined in FIG. 1 of the accompanying drawings, such a monochrome mask may be used to advantage in the preparation of the color separation positives employed to prepare the red, green, and blue reliefs. Similarly, in the process outlined in FIG. 2, a monochrome mask is advantageously used with the original image in exposing the red, green, and blue dye-sensitized media respectively employed for preparation of red, green, and blue reliefs.

Additionally, color-masking techniques can be employed to improve color tones in dye transfer prints, particularly in the process embodiment outlined in FIG. 2 of the accompanying drawings. The practice of color masking is made desirable by the imperfect color characteristics of the yellow, magenta, and cyan dyes commonly employed to form color images in subtractive color processes. For example, the cyan dye usually present in color positives has significant absorption in the green and blue portions of the spectrum, although ideally it should absorb mainly in the red. When an exposure is made through an unmasked color transparency using green light, the cyan dye present in the transparency absorbs some of this green light instead of transmitting it completely. This causes a resultant deficiency of green density in the final color print. Similarly, the magenta dyes commonly employed absorb more blue and transmit more green than is ideal.

These deviations in color tones can be corrected by the use of masking techniques involving a contact color mask made by exposing a normal contrast panchromatic film to light from a red filter through the positive transparency to be copied. in such a mask, a negative image is formed on development having its most dense portions corresponding with the reds, and having its least dense portions in those areas corresponding with the presence of a cyan dye in the original transparency. The negative mask so made is placed in register with the original transparency during exposure of the green dye-sensitized and blue dye-sensitized imaging media to green and blue light. In this manner, increased exposure through the cyan dye image areas of the original transparency is effectively obtained by decreasing exposure through the noncyan dye image areas when green or blue sensitizing light is used. This decreased exposure through noncyan image areas compensates for the unwanted absorption of green and blue by the cyan dye of the original transparency. Although good color reproduction can usually be obtained by the use of such a red filter color mask alone, further color correction is possible by preparation of a green filter mask and its use in combination with the transparency for the exposure of the blue-recording imaging medium.

As earlier mentioned, a highlight mask can also suitably be employed in the printmaking technique outlined in FIG. 2, conveniently by making a film-to-film contact negative print fromthe transparency using white light. This highlight mask is underexposed so that the top highlight present in the original has a density in the mask of the order of 0.1. The highlight negative can be bound in register with the transparency and used for the manufacture of the red filter color mask and/or green filter color mask earlier described. After the color masks have been prepared, the highlight mask is no longer required.

A better understanding'of the present invention and of its .many advantages can be had by referring to the following specific examples, given by way of illustration.

EXAMPLE 1 Preparation of a Photographic Imaging Medium Adaptable to the Manufacture of Direct Positive Photographic Relief Images 50 grams of an aqueous slurry containing 25 percent of finely divided titanium dioxide (about 0.3 0.4 micron) were diluted with 42.6 ml. of distilled water and 3.4 ml. ofa l0.percent solution of a commercial wetting agent (Tiwet The resulting mixture was heated to about F. and then combined with 100 grams of a 10 percent aqueous solution of gelatin swelled and heated to 100 F. 2.6 ml. of a 50 percent aqueous solution of glycerin were added to the resulting slurry as a humectant and antifoaming agent, and 2 mls. of a 4 percent aqueous solution of formaldehyde were added to the slur ry as a hardening agent for the gelatin. The resulting slurry was then uniformly poured onto a flat piece of subbed triacetate film and drawn down with a hot wire rod. The resultant hardened gelatin coating was dried for 20 minutes at room temperature and for another 20 minutes at about 50 C. in a circulating hot air oven.

EXAMPLE 2 Dye Sensitization of a Photographic Imaging Medium for Use With Color Separation Positives Sheets of the film prepared as in example i were dip-dyed for 2 minutes in an aqueous solution containing 100 mg. per liter of 2-(p-dimethylaminostyryl) 314 -3l4-dimethylthiazolium chloride,

which sensitizes the film to green light. The sensitizing dye here used acts also as a light moderator to control the depth of light penetration into the gelatin binder on exposure.

EXAMPLE 3 Exposure and Processing Using Color Separation Negatives A highlight mask is prepared in a manner known in the art by exposing a silver halide panchromatic film, in contact with a positive color transparency to be copied, to develop a maximum density in the contact printed negative mask of about 0.4.

The negative highlight mask is bound .in register with the transparency and the red separation negative is next made by conventionally exposing a silver halide film to red light through the transparency/highlight mask combination. In a similar fashion, green and blue separation negatives are made through the transparencey/mask combination using green and blue filters.

Red, green, and blue separation positives are next made by respectively contact printing the red, green, and blue separation negatives on three pieces of silver halide film.

Using three sheets of the photoconductor-containing film prepared and dye-sensitized according to examples 1 and 2 separate 5 exposures are made through the red, green, and blue separation positives using a 100 bulb at a distance of 12 inches. A green filter is also used in view of the dye-sensitization of this film to green light. The dye does .not serve any color separation function, which, in this embodiment, is the role of the color separation'positives.

The three exposed printing media were next developed by contacting with 3 N aqueous silver nitrate solution, briefly draining, and then contacting with an aqueous solution of 2 percent metol and 0.5 percent citric acid for 10 seconds to intensify the silver image. Each print was fixed in a standard acid hypo fixing bath and washed.

Each of the three films containing a silver image was next bleached for 2 minutes with a softening bleach of a type known in the art, prepared, for example, by combining one part by volume of a 3 percent aqueous solution of hydrogen peroxide with three parts by volume of an aqueous solution containing 75 grams ofCuSO -SH 0, 2 grams of KBr, 25 ml. of concentrated H SO.and water to make 1,500 ml. (cf. Glafkides, op. cit., p. 668 The bleach softens the gelatin in the silver image areas of the three imaging media respectively forming the red, green, and blue record, but leaves intact those portions of the gelatin binder where no silver is present. The three imaging media are next washed with cold water to remove softened gelatin to produce a set of three reliefs having unremoved gelatin in nonexposed areas.

EXAMPLE 4 Dye Transfer from the Relief Matrices The positive photographic relief containing the red record was submerged in water for 3 minutes to swell the gelatin. The relief matrix was then dipped for 10 seconds in a solution ofa commercial cyan transfer dye, Erio Fast Cyanine S (Sandoz Company):

ll 1 m4 0 3N5 l 0 NH:

The cyan dye image was then transferred by 5 second contact with a piece of preconditioned commercial (Kodak) transfer paper.

A similar dye transfer was made in register from the direct positive relief containing the green record, after taking up the commercial magenta dye Brilliant Alizarin Light Red B (Sandoz Company):

Finally, the positive relief containing the blue record was dyed with a conventional yellow transfer dye, 4- (4-hydroxy- 7 -sulfol -naphthylazo)- 3 -methyll -p -sulfophenyl pyrazolone disodium salt:

S OaNa Upon transfer of the yellow dye image to the receptor sheet in register, a full color dye transfer positive print of the original positive transparency was obtained.

EXAMPLE 5 Dye Sensitization of Photographic Imaging Media for Color Separation Exposures to a Positive Transparency Preparatory to the production of a full-color dye transfer print according to the method outlined in FIG. 2 of the drawings, a first sheet of an imaging medium prepared as in example 1 was dye-sensitized to red light by dip-dyeing for 2 minutes in a 0.015 percent aqueous solution of 1', 3- diethylthio- 4 -carbocyanlne chloride,

CgH

A second and third sheet of film were each sensitized by dipdyeing for 2 minutes in a 0.0] percent aqueous solution of Z-(p-dimethylamino styryl)-4 -methylthiazolium chloride,

011a Cl- This dye sensitizes the medium to green and/or blue light.

EXAMPLE 6 Exposure and Processing A highlight mask was prepared by contact printing a positive color transparency onto a panchromatic silver halide film. After development, the highlights of the original transparency had a maximum density of about 0.4 in the negative highlight mask. The mask and original transparency were bound together in register.

A red filter color mask was next made by exposing silver halide film to red light through the transparency/highlight mask combination. On development, the red color correction mask had a silver density range from O to about 0.6.

The red-sensitized film described in example 5 was now exposed to the transparency and color correction mask in register using light from a red Wratten filter 029 (transmitting from 600 700 millimicrons). The exposed film was then contacted with 3 N aqueous silver nitrate for 10 seconds, drained briefly, and then contacted with an aqueous solution of 2 percent metol and 0.5 percent citric acid for 10 seconds to intensify the image, utilizing silver ions still present on the surface of the film. This resulted in the production of visible black deposits of metallic silver in the imaging medium. The print was then fixed in a standard hypo fixing bath for 30 seconds and washed. The silver image was then bleached and surrounding portions of the gelatin binder softened using a bleaching and softening solution like that described in example 3 to give a red record direct positive relief.

A piece of the green and/or blue sensitized film described in example 5 was next exposed to green light using a 058 Wratten filter (transmitting 500600 millimicrons) employing the original positive transparency and the red filter color correction mask bound thereto in register. Exposure to the color corrected transparency compensated for unwanted absorption of green light by magenta dye present in the uncorrected transparency. Highlight correction was inherent in the greenexposed imaging medium because of the use of a highlight correction mask in preparing the red filter correction mask.

A metal image was developed in the green record by contact with aqueous silver nitrate followed by a metol/citric acid bath. Bleaching and softening of the gelatin and removal of softened gelatin followed to produce a green relief.

The second piece of blue and/or green dye-sensitized film was next exposed to the color corrected (masked) transparency with light from a 049 blue Wratten filter in combination with a Wratten 2 B filter (combination transmits 400 -500 millimicrons). The imaging medium was developed with silver ion, bleached, softened, and washed to form a blue record positive relief.

EXAMPLE 7 Dye Transfer from the Positive Reliefs The red direct positive photographic relief image was dipped for 10 seconds in a solution of the commercial cyan transfer dye mentioned above in example 4. Absorbed dye was then transferred by 5 second contact with a piece of preconditioned commercial transfer paper.

In a similar fashion, the magenta dye of example 4 was absorbed into the green positive relief prepared in example 6 and transferred in register with the earlier printed cyan image.

Finally, the conventional commercial yellow transfer dye of example 4 was absorbed into the blue direct positive relief prepared in example 6. The yellow dye was then transferred in register to the receptor sheet to produce a full color direct positive of the original image.

If desired, full color transparencies can be made by transferring dyes in register to a transparent receptor sheet, such as of mordanted subbed triacetate. A suitable mordant coating is prepared by swelling 45 grams of gelatin overnight in 55 ml. of water. The gel is then heated to 40 C. and 6 ml. of 50 percent poly- 4 vinylpyridine-metho-p-toluene sulfonate solution are added. The pH is adjusted to about 4.2 and 4.0 ml. of 10 percent formaldehyde are added. The mordant is poured onto subbed triacetate and drawn down. Mordant coatings of this nature are taught in patents such as U.S. Pat. No. 2,548,564

What is claimed is:

l. The method of making a direct positive photographic relief image adaptable to the making of dye transfer prints which comprises exposing a photographic imaging medium to imaging radiation, said imaging medium comprising a finely divided photoconductor which is reversibly activatable by actinic radiation dispersed in a gelatin binder therefor; developing radiation-exposed portions of said imaging medium with a developing agent comprising reducible metal ions, whereby free metal is deposited in said radiation-exposed portions; reoxidizing said free metal to metal ions in the presence of a metal ion-activated softening agent for said gelatin binder to soflen said gelatin binder in radiation-exposed area, and removing softened gelatin binder from radiation-exposed areas to produce said positive photographic relief image,

2. The method as in claim dye is takenup by those unremoved portions of binder defining said positive relief image.

3. The method as in claim 2 wherein takenup dye is transferred to a receptor sheet.

4. The method as in claim 1 wherein the dispersed photoconductor is dye sensitized.

5. The method as in claim 4 wherein said imaging medium comprising dye sensitized photoconductor is exposed to imaging radiation from a positive color image through a filter passing red, green, or blue light to which said photoconductor is sensitized.

6. The method as in claim 4 wherein said imaging medium comprising dye sensitized photoconductor is exposed through a color separation positive to imaging radiation to which said photoconductor is sensitized.

7. The method of making a fully color dye-transfer positive print which comprises respectively exposing three imaging media to imaging radiation from a set of red, green, and blue color separation positives, said imaging media each comprising a finely divided photoconductor dispersed in a supported layer of a gelatin binder therefor, said photoconductor being dye-sensitized to said imaging radiation; developing radiationexposed portions of said imaging media with a developing agent comprising reducible metal ions, whereby free metal is deposited in said radiation-exposed portions; reoxidizing said free metal to metal ions in the presence of a metal ion-activated softening agent for said gelatin binder to soften said gelatin binder in radiation-exposed areas; removing softened gelatin binder from radiation-exposed areas to produce a posi tive photographic relief image; respectively taking up cyan, magenta, and yellow dye in remaining portions of the gelatin binder of the relief images respectively prepared by exposure to said red, green, and blue color separation positives; and transferring dye from said relief images to a receptor sheet in register to produce said full color dye transfer print.

8. The method of making a full color dye transfer positive print which comprises respectively exposing three imaging media to imaging radiation from a positive color image through a red, green, and blue filter; said imaging media each comprising a finely divided photoconductor dispersed in a supported layer of a binder therefor, said photoconductor being dye-sensitized to said imaging radiation; developing radiation-exposed portions of said imaging media with a developing agent comprising reducible metal ions, whereby free metal is deposited in said radiation-exposed portions; reoxidizing said free metal to metal ions in the presence of a metal ion-activated softening agent for said binder to soften said binder in radiation-exposed areas; removing softened binder from radiation-exposed areas to produce a positive photographic relief image; respectively taking up cyan, magenta, and yellow dye in remaining portions of the binder of the relief images respectively prepared by exposure through said red, green, and blue filters; and transferring dye from said relief images to a receptor sheet in register to produce said full color dye transfer print.

a :1 =0 a a 

2. The method as in claim 1 wherein dye is takenup by those unremoved portions of binder defining said positive relief image.
 3. The method as in claim 2 wherein takenup dye is transferred to a receptor sheet.
 4. The method as in claim 1 wherein the dispersed photoconductor is dye sensitized.
 5. The method as in claim 4 wherein said imaging medium comprising dye sensitized photoconductor is exposed to imaging radiation from a positive color image through a filter passing red, green, or blue light to which said photoconductor is sensitized.
 6. The method as in claim 4 wherein said imaging medium comprising dye sensitized photoconductor is exposed through a color separation positive to imaging radiation to which said photoconductor is sensitized.
 7. The method of making a fully color dye-transfer positive print which comprises respectively exposing three imaging media to imaging radiation from a set of red, green, and blue color separation positives, said imaging media each comprising a finely divided photoconductor dispersed in a supported layer of a gelatin binder therefor, said photoconductor being dye-sensitized to said imaging radiation; developing radiation-exposed portions of said imaging media with a developing agent comprising reducible metal ions, whereby free metal is deposited in said radiation-exposed portions; reoxidizing said free metal to metal ions in the presence of a metal ion-activated softening agent for said gelatin binder to soften said gelatin binder in radiation-exposed areas; removing softened gelatin binder from radiation-exposed areas to produce a positive photographic relief image; respectively taking up cyan, magenta, and yellow dye in remaining portions of the gelatin binder of the relief images respectively prepared by exposure to said red, green, and blue color separation positives; and transferring dye from said relief images to a receptor sheet in register to produce said full color dye transfer print.
 8. The method of making a full color dye transfer positive print which comprises respectively exposing three imaging media to imaging radiation from a positive color image through a red, green, and blue filter; said imaging media each comprising a finely divided photoconductor dispersed in a supported layer of a binder therefor, said photoconductor being dye-sensitized to said imaging radiation; developing radiation-exposed portions of said imaging media with a developing agent comprising reducible metal ions, whereby free metal is deposited in said radiation-exposed portions; reoxidizing said free metal to metal ions in the presence of a metal ion-activated softening agent for said binder to soften said binder in radiation-exposed areas; removing softened binder from radiation-exposed areas to produce a positive photographic relief image; respectively taking up cyan, magenta, and yellow dye in remaining portions of the binder of the relief images respectively prepared by exposure through said red, green, and blue filters; and transferring dye from said relief images to a receptor sheet in register to produce said full color dye transfer print. 